The present invention generally relates to the field of devices such as pressure washers and the like that are capable of delivering a fluid from a supply source and discharging it at a greater pressure, and more particularly to an oilless high pressure pump suitable for use in such devices.
High pressure washing devices, commonly referred to as pressure washers, deliver a fluid, typically water, under high pressure to a surface to be cleaned, stripped or prepared for other treatment. Pressure washers are produced in a variety of designs and can be used to perform numerous functions in industrial, commercial and home applications. Pressure washers typically include an internal combustion engine or electric motor that drives a pump to which a high pressure spray wand is coupled via a length of hose. Pressure washers may be stationary or portable. Stationary pressure washers are generally used in industrial or commercial applications such as car washes or the like. Portable pressure washers typically include a power/pump unit that can be carried or wheeled from place to place. A source of water, for example, a garden hose, is connected to the pump inlet, and the high pressure hose and spray wand connected to the pump outlet.
Typically, pressure washers utilize a piston pump having one or more reciprocating pistons for delivering liquid under pressure to the high pressure spay wand. Such piston pumps often utilize two or more pistons to provide a generally more continuous spray, higher flow rate, and greater efficiency. Multiple piston pumps typically employ articulated pistons (utilizing a journal bearing and wrist pins) or may utilize a swash plate and linear pistons for pumping the liquid. Because these piston arrangements generate a substantial amount of friction (such as for example, sliding friction between the swash plate and pistons), existing pumps utilized in pressure washers must typically be oil flooded to provide adequate lubrication. However, such oil lubricated pumps have several drawbacks. For example, the lubricating oil must be maintained at an adequate level and typically must be periodically replaced. Neglect of such maintenance can result in damage to the pump. Further, the orientation in which the pump may be mounted to the pressure washer frame is severely limited.
Accordingly, the present invention is directed to an oilless high pressure pump suitable for use in devices such as pressure washers and the like to pump a liquid such as water or the like. In an exemplary embodiment, the pump includes an eccentric assembly suitable for converting rotary motion of a rotating shaft to rectilinear motion. One or more straps couple the eccentric assembly to the pump""s piston assembly. The straps communicate the rectilinear motion of the eccentric assembly to the piston assembly for reciprocating the pump""s pistons to pump the liquid.
It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.